A record of aerobic methane oxidation in tropical Africa over the last 2.5 Ma.

• Published in: Geochimica et Cosmochimica Acta
• Main Authors: Spencer-Jones, C.L., Wagner, T., Talbot, H.M.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Elsevier 2017
• Subjects: Arctic; Climate change; Global warming
• Online Access: http://dro.dur.ac.uk/23214/; http://dro.dur.ac.uk/23214/1/23214.pdf; https://doi.org/10.1016/j.gca.2017.08.042

Methane and CO2 are climatically active greenhouse gases (GHG) and are powerful drivers of rapid global warming. Comparable to the Arctic, the tropics store large volumes of labile sedimentary carbon that is vulnerable to climate change. However, little is known about this labile carbon reservoir, in particular the behaviour of high methane–producing environments (e.g. wetlands), and their role in driving or responding to past periods of global climate change. In this study, we use a microbial biomarker approach that traces continental aerobic methane oxidation (AMO) from sedimentary organic matter in deep-sea fan sediments off the Congo River to reconstruct the link between central African methane cycling and continental export during key periods of global Pleistocene warmth. We use 35-amino bacteriohopanepolyols (BHPs), specifically aminobacteriohopane-31,32,33,34-tetrol (aminotetrol) and 35-aminobacteriohopane-30,31,32,33,34-pentol (aminopentol) as diagnostic molecular markers for AMO (CH4 oxidation markers) and the prevalence of continental wetland environments. BHPs were analysed in sediments from the Congo fan (ODP 1075) dated to 2.5 Ma. High resolution studies of key warm marine isotope stages (MIS) 5, 11 and 13 are included to test the relationship between CH4 oxidation markers in sediments at different levels of elevated global atmospheric GHG.